Vapor delivery system useful with ion sources and vaporizers for use in such system

ABSTRACT

Vapor delivery systems and methods that control the heating and flow of vapors from solid feed material, especially material that comprises cluster molecules for semiconductor manufacture. The systems and methods safely and effectively conduct the vapor to a point of utilization, especially to an ion source for ion implantation. Ion beam implantation is shown employing ions from the cluster materials. The vapor delivery system includes reactive gas cleaning of the ion source, control systems and protocols, wide dynamic range flow-control systems and vaporizer selections that are efficient and safe. Borane, decarborane, carboranes, carbon clusters and other large molecules are vaporized for ion implantation. Such systems are shown cooperating with novel vaporizers, ion sources, and reactive cleaning systems.

TECHNICAL FIELD

This invention relates to the generation and delivery of vapor to vapor-receiving devices within high vacuum chambers. It also relates to delivery of ionizable vapor to high voltage ion sources that provide ion beams for ion implantation in the manufacture of semi-conductor devices and materials. It has particular relevance to systems and methods for vaporizing and ionizing materials that form molecular ions containing multiple atoms of a species of interest.

BACKGROUND

In industry it is frequently desired to deliver highly toxic, unstable material in vapor form to devices or substrate materials within a high vacuum system. It is necessary to periodically service such devices for cleaning or replacement of parts and to refill or replace the vapor sources and perform maintenance service. Each instance of refilling or service requires disengagement and re-engagement of vacuum seals and performance of re-qualification tests to ensure safety.

A particularly important example of such vapor delivery, having many stringent requirements, is the handling of doping materials for production of semiconductor devices. In this case it is necessary to produce vapor streams at accurately controlled flow from highly toxic solid materials that have low vapor pressure at room temperature. This requires careful heating of the solids to produce sublimation, and careful handling of the vapors because of risks of disassociation, unwanted condensation in the flow path and reaction of the vapors if brought in contact with other substances. Provisions to ensure personnel safety are also required. Improved systems for such vapor delivery are needed.

In particular there is need for improved vapor delivery for ion beam implantation systems in which the vapors ionized in an ion source produce an ion beam which is accelerated, mass-analyzed, and transported to a target substrate. With such ionization systems, it is especially desired to meet all requirements while prolonging the uptime, i.e. the time between required servicing. An advantageous way of doing this is by providing in situ cleaning of components of the system using highly reactive agents, but this introduces further safety concerns.

There is also need for safe and reliable vapor delivery systems that enable the same equipment to be employed with a number of different source materials that have differing vaporization temperatures.

There is further a need for a way to progress efficiently and safely from delivery of feed material obtained from a vendor to connection to a vapor receiving system of a vaporizer charged with the feed material. It is preferable that this be done in a standardized manner, to ensure familiarity to personnel.

Among the situations having all of the foregoing needs is the case of providing flows of decaborane and octadecaborane vapor, and vapor of carboranes, to an ion source at flows suitable to perform ion beam implantation to produce boron implants.

The needs also arise, more generally, in providing vapor flows of large molecules for semiconductor manufacturing. Examples include vapor flows: of large molecules for n-type doping, e.g. of arsenic and phosphorus; of large molecules of carbon for co-implanting processes in which the carbon inhibits diffusion of an implanted doping species, or getters (traps) impurities, or amorphizes crystal lattice of the substrate; of large molecules of carbon or other molecules for so-called “stress engineering” of crystal structure (e.g., to apply crystal compression for PMOS transistors, or crystal tension for NMOS transistors); and of large molecules for other purposes including reduction of the thermal budget and unwanted diffusion during annealing steps in semiconductor manufacture.

These needs apply to implementations employing ion beam implantation, and, where applicable, also to large molecule deposition of boron and other species for atomic layer deposition or producing other types of layers or deposits. Techniques for this may employ: plasma immersion, including PLAD (plasma doping), PPLAD (pulsed plasma doping) and PI³ (plasma immersion ion implantation); atomic layer deposition (ALD); or chemical vapor deposition (CVD), for example.

The needs just described and the inventive aspects now to be described apply importantly to the manufacture of high density semiconductor devices at shallow depth in semiconductor substrates, including CMOS and NMOS transistors and memory ICs, in the manufacture of computer chips, computer memory, flat panel displays, photovoltaic devices, and other products.

Other procedures in industry involving the generation and delivery of vapors or process gases to a vapor or gas consuming device can also benefit from features presented here.

SUMMARY

According to one aspect of invention, a flow interface device is provided in the form of a thermally conductive valve block which defines at least one vapor passage, the passage associated with at least first and second vapor transfer interfaces, one interface comprising a vapor inlet located to receive vapor from a vaporizer of solid feed material and communicating with an inlet portion of the passage, and the other interface comprising a vapor outlet for delivery of vapor from an outlet portion of the passage to a vapor-receiving device, the valve block having at least one vapor valve and constructed to heat the passage and deliver vapor from the vaporizer to the vapor-receiving device.

Implementations of this aspect may have one or more of the following features:

A vapor valve is a flow control valve for regulating the flow of vapor to a vapor-receiving device in the form of an ion source.

A vapor valve system enables vapor flow to an ion source of vapor entering through the vapor inlet and another flow to the ion source.

A flow enabled is flow of vapor from another vapor inlet defined by the valve block.

A flow enabled is flow to the ion source of a reactive cleaning gas.

Valves provided in the valve block comprise a first valve system enabling vapor flow to the ion source of vapor entering through a vapor inlet, and enabling flow to the ion source of vapor from another vapor inlet defined by the valve block, and a selector valve system enabling flow of vapor from a vapor inlet defined by the valve block, or, alternatively, closing all vapor flow and permitting flow to the ion source of a reactive cleaning gas.

At least two vapor inlets are defined by the valve block and located to receive vapor from respective vaporizers, the two vapor inlets associated with respective inlet passage portions, flows through the inlet passage portions being enabled by the first valve system, the inlet passage portions merging following the first valve system into a common passage portion, and the second valve system is arranged to selectively enable flow through the common passage portion to the vapor-receiving device, or, alternatively, flow of the reactive cleaning gas to the vapor-receiving device.

A further valve comprises a flow control valve associated with the common passage portion for regulating flow of vapor to the vapor-receiving device.

A valve of the valve system comprises a spool valve acting as a selector to permit only one of the flows at a time.

The valve block is associated with a heater controlled to maintain the temperature of the valve block higher than that of a vaporizer from which it receives vapor.

The valve block defines a mounting region constructed to receive and support a vaporizer.

Thermal insulation insulates the valve block from a vaporizer to define respective separate thermal control regions to enable maintenance of valve block temperature higher than that of the vaporizer.

A connector is constructed and arranged so that mounting motion of a vaporizer with respect to the valve block causes the connector to mate with a matching connector of the vaporizer, for connecting the vaporizer electrically to a heating control system.

The valve block defines a receptacle having support surfaces for receiving a support projection of a vaporizer to thereby support the vaporizer during vaporizer heating and vapor transfer.

The support projection is a lateral projection defining a lateral vapor flow passage, the projection having a peripheral side surface and an end surface, and peripheral and end thermal insulation portions are provided to enable thermal isolation of the valve block from the projection of the vaporizer.

The receptacle of the valve block is constructed to receive the support projection of the vaporizer by linear sliding motion of the projection, the flow interface device mounting an electrical connector that is constructed, with mounting motion of a vaporizer relative to the valve block, to slideably mate with a matching electrical connector of the vaporizer for connecting the vaporizer electrically to a control and heating system.

The electrical connector includes a pneumatic connector for supplying controllable compressed air to the vaporizer for selectively actuating a valve of the vaporizer.

The vapor valve is a flow control valve, the interface device being associated with a power supply and heating system for receiving sensed temperature signal from a vaporizer and for applying electric heating current to the vaporizer to cause the vaporizer to heat sufficiently to produce vapor of the solid feed material of pressure greater than that required by the vapor-receiving device, and in the range that enables the flow control valve to regulate vapor flow to the ion source.

The flow interface device is combined with a vaporizer, the vaporizer containing solid feed material capable of producing ionizable vapor.

The vapor-receiving device in the form of an ion source is constructed to produce ions for use in semiconductor manufacture.

The flow interface device is combined with an ion beam implanter in which the vapor-receiving device comprises a high voltage ion source capable of ionizing vapor to produce a beam of ions for ion implantation.

Solid feed material vaporized by the vaporizer comprises a cluster compound capable of producing vapor for the production of cluster ions.

The solid feed material comprises a cluster boron compound.

The compound comprises a borane or a carborane.

The cluster compound comprises B₁₀H₁₄, B₁₈H₂₂, C₂B₁₀H₁₂ or C₄B₁₈H₂₂.

The cluster compound comprises a cluster carbon compound.

The cluster compound comprises C₁₄H₁₄, C₁₆H₁₀, C₁₆H₁₂, C₁₆H₂₀, C₁₈H₁₄ or C₁₈H₃₈.

The cluster compound comprises a compound for N-Type doping.

The compound comprises an arsenic, phosphorus or antimony cluster compound.

The compound comprises an arsenic or phosphorus compound capable of forming ions of the form A_(n)H_(x) ⁺ or A_(n)RH_(x) ⁺, where n and x are integers with n greater than 4 and x greater than or equal to 0, and A is either As or P and R is a molecule not containing phosphorus or arsenic and which is not injurious to the implantation process.

The compound comprises a phosphorus compound selected from the group consisting of phosphanes, organophosphanes and phosphides.

The compound is P₇H₇.

The compound comprises an antimony compound that comprises a trimethylstibine.

The compound comprises S_(b)(CH₃)C₃.

The flow interface device and vaporizer are provided in combination with an ion beam implanter in which the vapor-receiving device comprises a high voltage ion source capable of ionizing vapor produced from the solid feed material for ion implantation.

A vapor-receiving-device is in the form of a high voltage ion source and the flow-interface device is mounted for support upon an electrical insulator.

The insulator is an insulator bushing that also supports the ion source to which the vapors are delivered.

The flow interface device is in combination with an ion beam implanter in which the vapor-receiving device comprises a high voltage ion source capable of ionizing the vapor to produce a beam of ions for ion implantation.

The flow interface device includes a gas purge system for removing vapor from the vapor inlet passage of the valve block prior to disconnecting the vaporizer from the valve block.

The valve block defines a delivery passage for a process gas.

The flow interface device is constructed so that a process gas is selectively directed through a passage through which reactive cleaning gas is at other times directed.

The valve block includes a delivery extension defining at least two flow paths to the vapor-receiving device, at least one of which is constructed to convey vapor from solid feed material and another is constructed to deliver a process gas or a reactive cleaning gas.

The flow control valve is a throttle type valve.

The valve system permits only one of the vapor flows at a time.

The valve system comprises a spool valve.

The flow interface device, for use with vaporizers containing the same feed material, comprises a valve system that permits flow from at least two vaporizers simultaneously. In some cases the valve system is constructed for a second mode of action in which the valve system permits only one of the vapor flows at a time.

According to another aspect of invention, a flow interface device for an ion source is constructed for use as the ion source for an ion beam implanter, the interface device being in the form of a thermally conductive valve block which defines at least one vapor passage, the passage associated with at least first and second vapor transfer interfaces, one interface comprising a vapor inlet located to receive vapor from a vaporizer and communicating with an inlet portion of the passage, and the other interface comprising a vapor outlet for delivery of vapor from an outlet portion of the passage to the ion source, the valve block constructed to heat the passage and deliver vapor from the vaporizer to the ion source, a flow control valve associated with the passage for regulating the flow of vapor to the ion source, and a valve system that enables vapor flow to the ion source of vapor entering through the inlet and another enables flow to the ion source.

Implementations of this aspect may employ one or more of the following features.

The flow interface device is associated with a power supply and control system for causing the vaporizer to heat sufficiently to produce vapor of the solid feed material of pressure greater than that required by the ion source, and in the range controllable by the flow control valve.

The flow control valve is a butter-fly type valve.

Another flow enabled is flow of vapor from another vapor inlet defined by the valve block.

Another flow enabled is flow to the ion source of a reactive cleaning gas.

The flow interface device includes at least two valve systems in the valve block that enable flow, a first valve system enabling vapor flow to the ion source of vapor entering through the vapor inlet, and enabling another flow to the ion source of vapor from another vapor inlet defined by the valve block, and a selector valve system enabling flow of vapor from a vapor inlet defined by the valve block, or, alternatively, closing all vapor flow and enabling flow to the ion source of a reactive cleaning gas.

The flow interface has vapor inlet passages associated with at least two vapor inlets located to receive vapor from respective vaporizers, controlled by a first valve system, following which inlet passage portions merge into a common passage, and the second valve system selectively controls flow through the common passage portion to the ion source, or alternatively flow of the reactive cleaning gas to the ion source, the flow control valve being associated with the common passage for regulating flow of vapor to the ion source.

A flow selection valve comprises a spool valve.

The valve block is associated with a heater controlled to maintain the temperature of the valve block higher than that of a vaporizer from which it receives vapor.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising solid feed material capable of forming ionizable vapor that comprises a cluster molecule.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising a cluster molecule.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising C₁₄H₁₄, C₁₆H₁₀, C₁₆H₁₂, C₁₆H₂₀, C₁₈H₁₄ or C₁₈H₃₈.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising N-Type doping.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising an arsenic, phosphorus or antimony cluster compound.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising arsenic or phosphorus compound capable of forming ions of the form A_(n)H_(x) ⁺ or A_(n)RH_(x) ⁺ where n and x are integers with n greater than 4 and x greater than or equal to 0, and A is either As or P and R is a molecule not containing phosphorus or arsenic and which is not injurious to an ion implantation process.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising a phosphorus compound selected from the group consisting of phosphanes, organophosphanes and phosphides.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising P₇H₇.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising an antimony compound that comprises a trimethylstibine.

Another aspect of invention comprises the generation, delivery and utilization of vapor from solid material comprising Sb(CH3)C3.

Another aspect of invention comprises a method of treating a semiconductor device or material comprising using the systems of any of the foregoing description to produce cluster ions, and using the ions in the treatment, especially a treatment comprising ion implantation and especially ion beam implantation.

According to another aspect of invention, a method of producing vapor employs the device or combination of any of the preceding disclosure.

Another aspect of invention comprises a system for producing vapor along a flow path from a group of vaporizers at mounting stations of a vapor delivery system comprising subgroups of vaporizers, one of the subgroups containing at least two vaporizers containing the same solid feed material and another group containing at least one vaporizer containing a different solid feed material, at least one vaporizer of the group containing material comprising a cluster molecule, the system including a control system enabling the subgroup of vaporizers containing the same solid feed material to simultaneously provide vapor along the path and preventing simultaneous flow through the path of vapor from the other subgroup.

In one implementation the system is an electro-mechanical control system.

In one implementation the system includes a vapor flow control that includes two variable conductance flow devices in series along the flow path, the down-stream device comprising a throttle valve and the up-stream device enabling adjustment of pressure of the vapor reaching the throttle valve.

Another aspect of invention is a system for producing vapor along a flow path from a group of vaporizers at mounting stations of a vapor delivery system comprising at least two vaporizers containing the same solid feed material of a cluster molecule wherein a control system is constructed to enable the two vaporizers to operate simultaneously.

In one implementation the system, and also useful with a single vaporizer, the system includes a vapor flow control that includes two variable conductance flow devices in series along the flow path, the down-stream device comprising a throttle valve and the up-stream control enabling adjustment of pressure of the vapor reaching the throttle valve.

Another aspect of invention is a method of producing ions for implantation comprising ionizing vapor received from any of the systems just described.

In one implementation the ions produced are formed into a beam for ion implantation.

The details of one or more implementations of the foregoing features are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side view of a vapor delivery arrangement comprising an external vaporizer, a vapor-receiving device within a high vacuum chamber and, between these components, a flow interface system.

FIGS. 1A, 1B, and 1C are diagrammatic illustrations of an implementation of a sealing feature at the high vacuum chamber of FIG. 1.

FIG. 1D is a schematic side view of a vaporizer useful in the system of FIG. 1.

FIG. 1E is a side view of another vaporizer. FIG. 1E also shows a portion of a vapor-receiving support member (that may be a flow interface device similar to that of FIG. 1) positioned to receive and support the vaporizer.

FIG. 1F shows the components of FIG. 1E when interfitted to support the vaporizer.

FIG. 1G is a side view of an implementation of the vaporizer of FIGS. 1E and 1F, with a removable thermal insulator jacket shown in phantom, while FIG. 1H is a vertical cross-section of the vaporizer through its center.

FIG. 1I is a side view and FIG. 1J is a top view of the bottom section of this vaporizer while FIG. 1K is a horizontal cross-section of the vaporizer, taken on line 1K-1K in FIG. 1H.

FIG. 1L is a diagrammatic, perspective view with part broken away illustrating heat transfer paths in the vaporizer unit while FIG. 1M is a magnified view of a portion of FIG. 1L.

FIG. 2 is a schematic bottom plan view of an arrangement having a flow interface system similar to that of FIG. 1, and which provides mounting stations for two vaporizers that supply vapor through a common vapor delivery path.

FIG. 3 is a schematic bottom view of an arrangement having a flow interface system similar to that of FIG. 2, and incorporating a flow control and vaporizer heating system by which a desired vapor flow from each of two vaporizers can be selectively sustained.

FIG. 4 is a schematic bottom view of an arrangement having a flow interface system similar to that of FIG. 2 that incorporates a reactive gas source and a flow-stopping device that prevents co-communication of flows.

FIG. 5 is a schematic side view of an arrangement having a flow interface system similar to that of FIG. 1, shown integrated with an ion source within a high vacuum chamber, and having an external reactive cleaning gas generator and a flow-stopping device that prevents co-communication of flows.

FIG. 6 is a schematic bottom plan view of an arrangement having an ion source system that has features of FIG. 5 combined with the flow control and dual vaporizer features of FIG. 3.

FIG. 6A is a valve and passage schematic drawing that implements features of FIG. 6 and includes a purge gas arrangement.

FIG. 7 is a view similar to FIG. 6, but showing installed two vaporizers of the type shown in FIGS. 1E to 1H. It also shows schematically a spool-type valve that enables selection of only one vapor passage at a time.

FIG. 7A is a top view and FIG. 7B a horizontal cross-section view of an implementation of the flow delivery system of FIG. 7.

FIG. 7C is a perspective view of an enclosed of system illustrating the opening a cover of the enclosed to access two vaporizers installed in the system.

FIGS. 8, 8A and 8B are orthogonal views of an implementation of a vapor delivery system within a housing, showing its relationship to an ion source high vacuum housing and ion source.

FIGS. 9, 9A and 10 are perspective views of the system of FIG. 8 illustrating the opening of a cover to access two vaporizers installed in the system.

FIG. 11 is a perspective view of the system of FIG. 8 with cover removed.

FIGS. 12 and 13 are perspective views from opposite directions of a vaporizer useful in a flow delivery system.

FIG. 13A through FIG. 13F are a sequence of diagrams illustrating different positions of a pneumatic valve and a manual over-ride device and fastening screws of the vaporizer.

FIG. 14 is a perspective view of the exterior of the vaporizer of FIGS. 1G and 1H, while FIG. 14A is a partial vertical side view in the direction of the axis of the connection features, FIG. 14B is a detail of the set of electrical connection pins shown in FIG. 14A, FIG. 14C is a vertical side view of the vaporizer of FIGS. 14 and 14A taken orthogonal to FIG. 14A, FIG. 14D is a top view of the vaporizer and FIG. 14E is a perspective view of a machine screw employed to assemble a cover to the top part of the vaporizer, and the top part to the bottom part of the vaporizer.

FIG. 15 is a vertical cross-sectional view of the vaporizer of FIG. 1G, similar to FIG. 14H, but on a smaller scale and showing also a portion of a flow interface device to which the vaporizer is mounted.

FIG. 15A is an exploded diagrammatic view of parts comprising a supported, thermally insulative connection of the projecting member of the vaporizer in a vapor receiving device such as that of FIG. 15, while FIG. 15B shows the parts assembled and FIGS. 15C and 15D are end views of the projecting member and of a circumferential insulative member, respectively, taken as shown in FIG. 15A.

FIG. 16 is a beam-current vs. mass plot of ions employing o-C₂B₁₀H₁₂ solid feed material in the vaporizer. It was produced with electron impact ionization according to the Horsky teaching referenced below, with system and in accordance with FIGS. 5 and 7-8.

FIGS. 16 and 16A are orthogonal, diagrammatic vertical cut-away views of the vaporizer of FIG. 14, taken on lines 16-16 and 16A-16A of FIG. 14D, showing the relationship of the open-permissive bar to the horizontal screws that fasten the vaporizer to the flow interface device.

FIGS. 17-17D are a series of perspective views illustrating steps of disassembling the vaporizer of FIGS. 1G and H to enable refilling prior to delivery to a customer.

FIG. 18 is a beam-current vs. mass plot of ions employing o-C₂B₁₀H₁₂ solid feed material in the vaporizer. It was produced with a electron impact ionization according to the Horsky teaching referenced below with system and in accordance with FIGS. 5 and 7 through 8.

DESCRIPTION OF EMBODIMENTS

Referring to FIG. 1, flow interface device 10 of a vapor delivery system is connected to high vacuum chamber 20 and comprises a portion 8 located outside of the vacuum chamber and an extension 9 protruding into the vacuum chamber. Portion 8 of interface device 10 provides a mounting station 12 at which an external vaporizer 14 is removably mounted at a gas-tight interface I.

Vaporizer 14 is of canister type having a bottom section, which contains a charge of solid feed material to be vaporized, and a removable top member. The top member is associated with a vaporizer heater shown diagrammatically at 19. The interface system includes a heater control circuit 33 which controls power P₁₄ to the vaporizer heater which produces vapor from the feed material. A vapor flow path 16 extends in the interface device 10 from the vaporizer via the interface I, through an adjacent stop valve 15, thence through portion 8 and extension 9. The extension 9 is sealed to the housing of vacuum chamber 20 at vacuum-tight seal 21.

A sealed disengageable connection is formed between extension 9 and vapor-receiving device 22 within the high vacuum chamber. This point of connection is referred to as interface II.

With this arrangement, ready removal and servicing of both the external vaporizer 14 and the vapor-receiving device 22 is made possible without disturbance of the seal 21 at the connection of the flow interface device 10 to the housing of high vacuum chamber 20. Despite repeated flow disconnection and reconnection at interface II for performing service on vapor-receiving device 22, interface II does not present a potential leak hazard to workers because of its location. To any extent that leak may occur, the leakage is confined within high vacuum chamber 20 and is removed by its vacuum pump and associated effluent treatment system 25.

In preferred implementations of the system, at interface II, the connection is made within the high vacuum chamber by installation movement of the vapor-receiving device. In the example of FIG. 1, the vapor-receiving device 22 is installed by moving along path A until device 22 seals upon a surface of the vacuum chamber 20 at detachable connection 23. As it is installed with this motion, the vapor-receiving device 22 is constructed to engage and seal with extension 9 at interface II within the vacuum chamber 20. For instance, it may be constructed to form, effectively, a labyrinth vacuum seal by matching close-fitting surfaces. Similarly, the vapor receiving device 22 is constructed to be removable from the vacuum chamber by opposite motion along path A in a manner that breaks the seal at interface II, without disturbing the seal 21 of flow interface device 10 with the housing of vacuum chamber 20.

FIGS. 1A-1C illustrate a mechanism that forms such a seal at interface II within high vacuum chamber 20′. The housing of high vacuum chamber 20′ includes an interface flange 20F joined in vacuum-tight manner to the housing and having an opening directed downwardly.

Flow interface device 10′ is in the form of a thermally conductive block that defines a vapor flow passage. It includes a collar 6 constructed to mount the block upon housing flange 20F in vacuum tight manner. A neck member 7 joined and sealed to block 10′, defines an extension of the vapor passage. Neck member 7 protrudes from the collar 6, through chamber flange 20F, into the high vacuum chamber 20′.

A spring-loaded connector seal member 5, e.g. of Teflon, has a tubular stem 5A closely fitted inside a cylindrical portion of the passage in neck member 7. The stem 5A extends upwardly into the installation path of vapor receiving device 22′, terminating in a top head 5B that defines a horizontal upwardly directed sealing surface. Head 5B has a corner cam surface 5C, disposed to be engaged by a corresponding cam surface 22C of device 22.

In FIG. 1A, cam surfaces 5C and 22C′ are shown still separated as the vapor-receiving device 22′ moves to the right along path A for installation. In FIG. 1B, the device 22′ has advanced to the point that the cam surfaces engage. In FIG. 1C installation is complete with the mounting flange of device 22′ seated upon a corresponding flange surface of high vacuum chamber 20′, forming vacuum tight seal 23. The spring-biased Teflon member 5 has been pushed downwardly and its flat top surface engages a corresponding downwardly directed flat surface of device 22. These mating surfaces in effect form a labyrinth seal. Another labyrinth seal is formed by the close fitting cylindrical surfaces of the passage in neck member 7 and the stem 5A of the connector 5. With the flow-receiving device 22′ seated, the passages of neck member 7 and the vapor-receiving device 22′ are aligned to enable delivery of vapor.

For removal of the vapor-receiving device 22′, the motions are reversed.

It will be understood by those skilled that other docking configurations can be employed, one example being engaging surfaces that are axially-aligned, e.g. surfaces of conical or pyramidal connectors. In other cases, after the vacuum-receiving device has been seated, a reversible actuator mechanism may be activated to complete a sealed connection between the parts within the vacuum housing.

Referring again to FIG. 1, in preferred implementations, flow interface device 10 is constructed to accept vaporizers containing different materials to be vaporized. Each vaporizer carries a temperature sensor by which the temperature T₁₄ of the vaporizer is sensed and sent to vaporizer heater control circuit 33 of the interface system. While shown sensing the temperature of the top of the unit, it may instead be located to sense the temperature near the bottom, with advantages, or both locations may be monitored. Each vaporizer is dedicated to a particular source material and carries an identifier device 30. The flow interface device 10 has a complementary recognition device 32. Recognition device 32 provides a control signal C₁₄ to vaporizer heater control circuit 33, in response to which control circuit 33 establishes a safe temperature range for heating the respective feed material including an upper limit for applying power to the heater of the particular vaporizer. As an example, in a preferred implementation, flow interface device 10 is constructed to receive vaporizers 14′ and 14″ dedicated to containing, respectively, decaborane and octadecaborane. The vaporizers carry distinctly different identifying devices 30. When a vaporizer is mounted to interface device 10, the recognition device 32 recognizes the vaporizer 14′ or 14″ and provides respective control signal C₁₄′ or C₁₄″. In a suitable implementation, the recognition signal C₁₄′, triggered by a decaborane vaporizer, enables the heater control circuit 33 to operate within an appropriate heating range for vaporizing decaborane and prevents heating of the vaporizer above about 35 C, while the recognition signal C₁₄″, triggered by an octadecaborane vaporizer, enables the heater control circuit 33 to operate within an appropriate heating range for vaporizing octadecaborane and prevents heating of the vaporizer above 135 C, for example. Other vaporizers dedicated to other materials carry other identifiers that are recognizable to cause the interface control unit to enable other temperature ranges or other appropriate operating conditions.

In preferred implementations, flow interface device 10 comprises a thermally conductive body, formed for instance of machined aluminum block-forming parts. When valves are installed, the thermally conductive block serves effectively as valve body for the valves. A vacuum-tight vapor path through the heated body extends from interface I to interface II. The body is in thermal contact with a heater shown diagrammatically at 11, controlled by circuit 13. Circuit 13 has temperature inputs T₁₄ from vaporizer 14 and T₁₀ from the conductive body of flow interface device 10. Circuit 13 is adapted to control heater 11 to maintain the conductive body at a controlled temperature, for instance, to a temperature above the temperature of the respective vaporizer 14, but below a safety temperature, e.g., a temperature below disassociation temperature of a respective material being vaporized.

The heaters of the system may be of various forms, for instance conventional electric cartridge or band heaters, and may be arranged in one or more than one heating zone. For instance, advantageously, there may be a heating zone 1 for heating the vaporizer to T₁, heating zone 2 for heating the interface body 10 and heating zone 3 for the vapor-receiving device 22. The heating zones are comprised of respective heater elements and temperature sensors, that, in one arrangement, increase in temperature from T₁ to T₂ along the path from vaporizer to interface II in the vapor receiving device, i.e. T₁<T₂<T₃ where all of these temperatures are limited to a temperature T₄ below a safety limit for the material to be vaporized.

Referring to FIG. 1D, in preferred implementations the vaporizer is a canister comprising a thermally-insulated canister body 14A as bottom section or member and a detachable top section or closure member 14B. Body 14A has a top opening and a volume, for instance, of 1 liter, for holding a charge of solid feed material that is to be progressively sublimated. Detachable top member 14B incorporates a valve V1. The top and bottom members, and preferably the valve as well, are comprised of thermally conductive material, for instance aluminum. The valve is located within the body 14B of the top member, by which it is maintained substantially at the temperature of the body.

Advantageously, only the top member of the vaporizer unit is electrically heated. Solid material within the canister body is heated to a major extent by heat transfer through the joint between the detachable top and bottom sections and through the side and bottom walls of the bottom section which are heated by conduction from the heater. In this manner it is ensured that the temperature T₁ of the vapor passage through the top member exceeds the temperature of the solid source material being sublimated.

As previously mentioned, placement of the heater in the detachable top closure section of a vaporizer-canister unit, whereas the charge of material to be vaporized at varying temperature is located in the bottom of the unit, might not appear to be good practice to those of ordinary skill. Thermal resistance of the interface between the detachable top and the bottom sections and the distance for the heat travel with associated thermal mass and slowness of response as well as heat loss to the exterior would appear undesirable. However, it is found that significant advantages are obtainable with this arrangement and what might seem to be inherent disadvantages are found avoidable or inconsequential in suitable implementations.

Thus the system ensures that vapors produced from the material encounter passages of increasing temperature while moving from the point of generation through valve V1 and to and through flow interface device 10. Similarly the part of the vapor-receiving device 22 that precedes the point of vapor utilization may define another heating zone adapted to be held at a temperature incrementally above that of the flow interface device 10.

Referring now to the plan view of FIG. 2, the flow interface system has all the features of the system of FIG. 1, some not shown, and also defines multiple vaporizer mounting stations. Two are shown, stations 12A and 12B.

Individual flow path segments 16A and 16B extend partially through the length of portion 8 of the thermally conductive body of device 10A, respectively, from the mounting stations 12A and 12B. Paths 16A and 16B merge at junction X. A common vapor flow path segment 16C extends through the remainder of portion 8A and through extension 9 of interface device 10A to interface II where the vapor is delivered to vapor-receiving device 22. Stop valves 15A and 15B in device 10 are associated with the individual flow paths 16A and 16B. As indicated by link 17, valves 15A and 15B are interlocked. This is done, in the case shown, in a manner that ensures each valve must be closed before the other can be opened. This prevents simultaneous flows from paths 16A and 16B.

The flow interface device 10A thus provides ready access for removal and servicing of two vaporizers without disturbance of the sealed connection 21 of interface device 10A with the high vacuum chamber 20; it permits one vaporizer to be serviced or filled, while another, containing the same source material, produces vapor and permits vaporizers of two different species to be installed for selective use. By providing, at Interface I, thermal isolation of the vaporizer-canister from the remainder of the system, an inactive unit is enabled to cool so that any charge of material remaining in the unit does not substantially degrade.

Referring to FIG. 3, the flow interface system has all features of the system of FIG. 2, some not shown. Also, in common path 16C, the flow interface device 10B of FIG. 3 includes flow control device or throttle valve 24 followed by pressure monitor 26. These are connected to flow and heater control device 28 of the interface system. Control device 28 is connected to temperature sensing lines T_(14A) and T_(14B) and heater power lines P_(14A) and P_(14B) for the respective vaporizers 14A and 14B. Recognition devices 32A and 32B at the mounting stations interact with identity devices 30A and 30B on vaporizers 14A and 14B dedicated to particular source materials. The recognition devices communicate the identities of the types of vaporizers to the flow and heater control system 28, causing the latter to select proper operating limits, and application of appropriate power to the respective vaporizer heaters 19.

The flow control device 24 in common path C may comprise a throttle valve such as a butterfly valve that varies the vapor conductance of the passage. The control system may be constructed to operate in accordance with the protocol described in the patent application WO 2005/060602 published 7 Jul. 2005, entitled “Controlling the Flow of Vapors Sublimated from Solids”, the entire contents of which are hereby incorporated by reference.

In particular, the operation of such a throttle valve to deliver a desired flow depends upon there being a desired pressure of vapor in the region immediately upstream of the throttle valve. It is to be noted that at a given vaporizer temperature, the amount of the vapor generated and hence its pressure, is dependent upon the amount of the charge of feed material that remains in position to be heated to vaporization temperature. To compensate for progressive depletion of the original charge of material, the control system senses delivered pressure and increases the temperature of the vaporizing chamber accordingly. It is advantageous for the vaporizer system to be capable of achieving the increased temperature without great delay. This is important during operation and is especially important during start-up when the operating pressure and heating system is being tuned to achieve desired performance of the overall system.

The single flow control device 24, being situated in the common path segment 16C, is capable of selectively controlling flows from two or more vaporizers at respective mounting stations. By interlocks, including the selected position of linked valves 15A and 15B as described in FIG. 2, the system may be prevented from heating and transmitting vapor from more than one vaporizer at a time. The selected vaporizer, device 10B and device 22 are constructed to be heated to the appropriate temperatures, e.g. T₁<T₂<T₃, where all of these temperatures are limited to a temperature T₄ below a safety limit for the particular material in the vaporizer selected. Thus, it is ensured that heating is applied in the pre-determined safe range appropriate for the material in the selected vaporizer, and that other conditions relevant to that material are properly controlled.

Referring to FIG. 4, a system is shown which may have all features of the system of FIG. 2 or 3, some not shown, and is provided with a reactive cleaning gas source 40 which communicates with passage 42 in portion 8C of the body of flow interface device 10C. An extension 9A of the flow interface device is sealed to a wall of the high vacuum chamber 20A and protrudes into the high vacuum chamber 20A to interface II-A. It defines two separate flow paths to the vapor receiving device 22A, path 16C for flow of vapor from the common vapor path and parallel but separate path 42 for flow of reactive cleaning gas. Sealed connection with corresponding passages 22V and 22G of the vapor-receiving device 22A are removably formed at interface II-A; each may be formed by labyrinth seals in the manner previously described. Leakage from either seal can be contained by the surrounding walls of high vacuum chamber 20A.

If implemented according to FIGS. 1A-1C, for instance, installation and removal movements of vapor-receiving device 22A along path A, can make and disconnect sealed connection of both vapor and reactive gas passages through extension 9A. Close-fitting surfaces of the matching parts can effectively form the labyrinth vacuum seals as previously described.

The reactive cleaning gas source 40 may be a container of reactive gas or a means for generating a reactive gas from a gaseous or solid feed material.

The interface device 10C of FIG. 4 includes a valve interlock 50 that prevents simultaneous flow of vapor and reactive cleaning gas to vapor receiving device 22A. In a preferred implementation, this is achieved with a reciprocal spool valve, which ensures that each path is completely closed before the other path is opened. In an alternative construction not shown, in which the reactive gas source 40 is a reactive gas generator that has a feed gas supply line for feed gas to be disassociated, the interlock can be formed with the feed supply line to the gas generator rather than with the reactive gas line, in a manner that can disable the supply line. In this case, the reactive gas connection with the vapor-receiving device may be separately formed.

Referring to FIG. 5, an adaptation of the general scheme of FIG. 1 is shown in which the vapor-receiving device comprises a high voltage ion source 22B, having an ionization chamber 90 into which a controlled flow of vapor is introduced to be ionized. Ions are withdrawn from ionization chamber 90 though an extraction aperture 92 by electrostatic attraction of an extraction electrode and final energy assembly 94 to form ion beam 96. The beam is directed along a beam line to an ion implanter end station, not shown. The high vacuum chamber of FIG. 5 comprises an ion source vacuum housing 70 that is provided with a high voltage insulator 62, for instance of reinforced epoxy. Insulator 62 electrically isolates the main vacuum housing member 71 from the high voltage end at which is mounted the ion source 22B and its vapor feed system 10D and 14. A vacuum-tight mounting ring 72 is provided on the high voltage side of insulator 62. It provides an end flange 74 for removably receiving and sealing with mounting flange 76 of ion source 22B. The ion source structure extends axially along axis A from the mounting flange into the vacuum chamber. As shown in FIGS. 4 and 5, the extension 9B of flow interface device 10D is of two-passage construction and is sealed at 21A to mounting ring 72. It protrudes into the high vacuum chamber to interface II-B. By constructing the interface for each passage of extension 9B according to FIGS. 1A-1C and FIG. 4, for instance, this interface can be positioned to receive the removable ion source via a connection that effectively form seals for each passage, for instance by close-fitting surfaces forming, effectively, labyrinth vacuum seals, in the manner previously described.

A reactive gas source in the specific form of a reactive cleaning gas generator 40A has a feed line 41 for a material, for instance a gaseous fluoride compound capable of being disassociated. The cleaning gas generator is constructed to provide disassociating conditions by which a reactive cleaning gas is generated, for instance, fluorine or fluorine ions. Its output is introduced to feed passage 42 in interface device 10D. As in FIG. 4, reactive gas passage 42 and the vapor flow path 16 pass through an interlock device 50, such as a spool valve, that selectively permits flow through only one passage at a time, preventing simultaneous flow. Advantageously a throttle valve 24 and pressure monitor 26 and associated controls, such as provided in FIG. 3, are provided in the flow interface device 10D. The reactive cleaning gas generator may comprise a plasma chamber or other apparatus capable of producing reactive gas cleaning from solid or gaseous feed material.

The system of FIG. 5 may readily be incorporated in each of the ion implanter systems shown in the published application WO 2005/05994 entitled “Method and Apparatus for Extending Equipment Uptime Ion Implantation,” the contents of which, in this regard, are hereby incorporated by referenced as if fully set forth herein.

Referring to FIG. 6, an ion source 22B and vapor delivery system (14-1, 14-2, and 10E) similar to that of FIG. 5 may have all features of the systems of FIGS. 1-5, some not shown. In FIG. 6, two mounting stations are defined for solids vaporizers 14-1 and 14-2 for producing ionizable vapor. The system may have all interlocks and safety features so far described, and a control system constructed to control heating of the vaporizers and flow though the interface device 10E. A source of ionizable gas 100, such as gas of a monatomic doping species, is also provided having a conduit 102 associated with the interface system. It makes connection with the reactive gas passage 42A at a point downstream of the interlock 50. This downstream portion of gas passage 42A for reactive cleaning gas and the related reactive gas passage of extension 9A is thus alternately useful for introducing an ionizable material that is gaseous at room temperature for providing other dopant species. An interlock, not shown, may be provided to prevent flow of ionizable source gas when flow of ionizable vapor or cleaning gas is occurring.

The schematic of FIG. 6A indicates that the flow features of FIG. 6 are incorporated in a conductive block 120. Also incorporated in the block are purge gas passages that enable purging the block e.g., with argon while the block is heated. This can remove vestiges of toxic or reactive vapor before servicing the system or before introducing vapor of another species. As indicated in FIG. 6A, this system in particular is suitable for providing boron-containing vapor B_(x), e.g. decaborane and octadecaborane, from vaporizer bottles to an ion source 22B of an ion implanter.

The vapor system of FIG. 6A has a purge capability similar to techniques used for toxic gas boxes. The valve on the solids vaporizer canister, V1 or V2, is constructed to be remotely operated. It can thus be remotely closed to isolate the vaporizer. The interlocked vaporizer selector valves V3 and V4 (realized, for instance, in the form of a spool valve unit) also is operated to isolate the vapor delivery path from the vaporizer. A gas cavity is thus created between the bottle isolation valve and vaporizer selector valve. This gas cavity will contain residual vapor, e.g. B_(x) vapor. Prior to vaporizer disconnection for removal, by appropriate actuation of valve V5 or V6, the cavity is cycle-purged with argon through common line 16C to eliminate any trace of B_(x) vapor that otherwise might escape to the environment.

The system shown schematically in FIG. 7 and implemented in FIGS. 7A and 7B may be the same as that shown in FIG. 6 and has further features.

All connections to the canisters are formed at Interface I. This includes electrical power connections for powering the vaporizer heaters, signal connectors for signaling temperature and other parameters of vaporizer status and compressed air, for controlling the pneumatic valve within each vaporizer canister.

Like FIG. 6A, in FIGS. 7, 7A and 7B, interlocked valves V3 and V4 are provided for the vapor passages from the two vaporizers (vaporizers 14′ in FIG. 7, vaporizers 14″ in FIGS. 7A and 7B). The interlock is shown implemented by valve elements V3 and V4 being portions of a spool valve similar to the spool valve 50 of FIG. 6. The purge gas feature of FIG. 6A is included.

For enabling flow from the vaporizers, the strict controls needed to prevent mixing of dangerous combinations of vapors can be subject to pre-established protocols, implemented by control logic in an electro-mechanical control system. Similarly, mechanical interlocking mechanisms may have provisions for altering modes of operation. In some cases, controls are established that absolutely prevent communication between vaporizers, or between selected vaporizers. They may on the other hand implement permission for simultaneous flow of some vaporizers. A case where this is appropriate and useful is where the vaporizers contain the same feed material. For example, a simultaneous flow may be employed when a charge in one vaporizer is nearing depletion and while it is desired for economic reasons to utilize the entire charge, it is also desired to commence use of a replacement vaporizer. Such strategy has advantage in ensuring a plentiful supply of vapor, while not pushing the heating limits of a nearly-spent vaporizer. Referring to FIG. 7C, a flow interface device defines mounting stations for four vaporizers (or more), each connected to a respective stop valve, and all communicating by common passage to a flow control system. Examples for interlocking control logic: Example 1: Vaporizers 1 and 2 are permitted to be on service at the same time, or Vaporizers 3 and 4 are permitted to be on service at the same time. Example 2: Vaporizer 1 or 2 or 3 or 4 can be on service at the same time.

In the implementation shown in FIG. 7C, two variable impedance flow control devices, 24A and 24B such as throttle valves, e.g. butterfly valves, operate to enable a higher upstream vapor pressure, and effectively achieve a broader dynamic range than a single unit, so that both high and low vapor flows may be achieved.

FIGS. 8-11 show an implementation that combines all features of a flow interface device so-far described. As shown in FIGS. 10 and 11, a flow interface device, in the form of a thermally conductive body comprising a valve block 130, is mounted below the installation-and-removal path A of an ion source 22B, shown in FIGS. 8 and 9. Valve block 130 defines two mounting stations for vaporizers 132 and 134 of heated canister form, which hang from the flow interface device by mounting features incorporated in their top sections. Valve block 130 has individual flow passage segments from these mounting stations, that merge to a common passage segment that leads into the high vacuum chamber 71A, FIGS. 8 and 8B.

As shown in FIGS. 8 and 11, and similar to features shown in FIGS. 1A-1C, the interface device 130 is suspended, by its collar 6A, from a mounting flange 72F that forms part of vacuum housing mounting ring 72A. Thus the system is suspended on the high voltage side of high voltage insulator 62A. Its flow passages connect to the ion source structure via a cammed connector within the vacuum housing as shown in FIGS. 1A-1C. A reactive cleaning gas source, in the form of a plasma chamber 40 A′, is suspended from the valve block 130, below it. It is constructed to disassociate a feed gas to produce reactive fluorine. In one preferred form, the weight of this entire assembly is carried by ion source mounting ring 72A, which in turn is supported by insulator 62A.

Incorporated in the valve block 130 are cartridge heaters and valves that perform the safety and flow heating and control functions of the heater and valves described with respect to the previous figures. A sheet metal enclosure 140 surrounds this delivery assembly, and has covers, including vaporizer cover 142, that can be opened for access. This enclosure is supported from the floor by feet comprising high voltage insulators. Thus the entire vapor delivery system is adapted to be maintained at the high voltage potential of the ion source.

It will be understood that numerous other physical arrangements are possible that still provide the actions described at one or the other sides of a mounting ring connected to the insulator and still out of the path of installation and removal of the ion source.

Referring to FIG. 11, vaporizer units 132 and 134 are shown. Each has a heater, as in FIG. 1D and is constructed to contain and heat a solid feed material such as decaborane or octadecaborane to a temperature that produces vapor to be ionized. As with the unit of FIG. 1D, the vaporizer unit comprises a lower canister body 14A having a solids-receiving volume, typically about a liter, and a detachable top closure member 14B. It is constructed to hang vertically from the top closure member at a suitable mounting station. For this purpose, the top closure member defines a vertical mounting surface to match and seal with a corresponding surface of the mounting station defined by the flow interface device 10, FIG. 1, or its valve block implementation. Top member 14B of the canister of FIGS. 1D and 11 also incorporates a valve V1 that permits vapor flow from the canister to the mounting station. Top member 14B is formed of thermally conductive material, e.g. aluminum.

The heater 19 of this vaporizer preferably comprises a set of cartridge heater elements fit into receptacles formed in the top member 14B. Importantly, this heater, located in the detachable top member is found to provide sufficient heat to vaporize the solids properly. By its location, it serves to maintain the valve of the top closure member at temperature higher than the temperature to which the solid material is heated. Advantageously, for this purpose, the body of valve V1 is comprised of thermally conductive aluminum and disposed in conductive heat transfer relationship with the heater, via the aluminum top member to maintain the vapor passage through the valve substantially at heater temperature.

In preferred implementations, there is only one controlled heating zone for the vaporizer. With these features in combination, it is found that the heater located in the top section of the vaporizer-canister can produce efficient vaporization of the remote charge in the lower section as the charge is consumed. The construction is found to have a sufficiently low thermal mass so that acceptably fast equilibration to a set temperature can occur. This permits proper operation and sufficiently rapid change in temperature setting as an operator adjusts parameters to initiate or tune the operation of the overall system.

In particular, the unit is found useful with pressure-based throttle valve vapor flow control 24, implemented e.g. with a butterfly valve, in which the vaporization temperature must be gradually increased as the charge of feed material is consumed to maintain the pressure upstream of the throttle valve, see FIGS. 3, 6, and 7 and related description.

Furthermore, and very importantly, the positive temperature gradient from bottom to top of the vaporizer unit that is attainable with this heat transfer arrangement prevents condensation of the vapor and build-up of disadvantageous deposits in the vapor valve V1 (located at the transition from vertical to horizontal flow) and the vapor delivery passage (upward inlet passage and horizontal delivery passage). These features are strategically located close to the heater, with temperature dependably being higher than the temperature of the charge of material in the bottom of the remote vaporization cavity.

In more detail, the rising passage terminates at a horizontal valve seat. The horizontal vapor passage then extends from the valve. Top part 14B houses pneumatic bellows valve (V1 in FIG. 1D, V1 or V2 in FIG. 6A) and a portion of the “open permissive” mechanism referred to “Mechanical override mechanism” in FIG. 1D.

Cartridge heaters of suitable type may be employed in the top section 14B of the vaporizer and in the valve block flow interface device 10.

Suitable RTDs (resistive thermal detectors) are located at the bottom of the vaporizer-canister unit and elsewhere in the system. A conductive lead for signal from the bottom sensor extends to a connector at the interface with the top section 14B. This connector is laterally aligned with a mating connector of the top section by bringing the overall mounting devices of the unit into alignment with those of the bottom section, and movement of the aligned top section down to engage the bottom section engages the connector.

The top of the regulated temperature range for the RTD temperature sensor, controlled by the remote thermal control unit, in one example, may be set at 40 C for B₁₀H₁₄ and 120 C for B₁₈H₂₂, and, for one example, an over-temperature limit switch in the top of the vaporizer-canister unit may be set at 50 C for a B₁₀H₁₄ vaporizer-canister and 140 C for a B₁₈H₂₂ vaporizer-canister. Similar temperature settings are employed with other feed materials, the particular values being dependent upon the vaporizing properties of the chosen material

As previously indicated, separate thermal zones are established to prevent heat migration between the vaporizer canister and the vapor-receiving device, accomplished by introduction of a substantial thermal break. This prevents heat entering the vaporizer unit from the vapor-receiving device and interfering with the thermal control system of the vaporizer-canister unit. Also, because of presence of this thermal break, a mounted vaporizer-canister unit can cool relatively quickly after being de-energized and its outer thermal insulation removed, despite the vapor-receiving device to which it is mounted being hot and continuing operation at temperature with another attached vaporizer unit. Despite continued heated state of the flow interface device (valve block), workmen can soon handle a de-energized vaporizer-canister unit for removal and replacement. Alternatively, the cooled unit may be left in place while avoiding substantial thermal degradation of remaining charge of feed material that otherwise would occur due to heat from the interface device.

The system described is suitable for safe production of ion beams from large molecule feed materials, including boron containing compounds such as decaborane (B₁₀H₁₄) and octadecaborane (B₁₈H₂₂).

As described, the system of FIG. 7 has two sources of gas delivery, gas from the reactive cleaning gas source and vapor from the vapor delivery system. The isolation valves V7 and V8 that deliver NF₃/F and B_(x) to the ion source are mechanically linked (realized, for instance by a spool valve unit) such that these two streams are never allowed to be cross-connected.

A. Applications

In general, any material which can provide a flow at least in the 1 sccm range, at temperature between about 20 C and 150 C is a candidate material for use in the vaporizer units and with the vapor delivery system constructed according to principles described above.

The embodiments of vaporizer and vapor delivery system specifically described have been demonstrated to be particularly effective for providing flows of decaborane and octadecaborane vapor and the vapor of carboranes to an ion source at flows suitable to perform ion beam implantation, to implant boron which achieving a degree of amorphization.

The principles are applicable more generally to providing vapor flows of large molecules of many descriptions in a host of applications in semiconductor manufacturing. Examples include vapor flows: of large molecules for n-type doping, e.g. of arsenic and phosphorus; of large molecules of carbon for co-implanting processes in which the carbon inhibits diffusion of an implanted doping species, or getters (traps) impurities, or amorphizes crystal lattice of the substrate; of large molecules of carbon or other molecules for so-called “stress engineering” of crystal structure (e.g., to apply crystal compression for PMOS transistors, or crystal tension for NMOS transistors); and of large molecules for other purposes including reduction of the thermal budget and unwanted diffusion during annealing steps in semiconductor manufacture. The principles have been demonstrated in the laboratory to apply to boranes, carbon clusters, carboranes, trimethylstibines, i.e., Sb(CH3)C3, arsenic and phosphorus materials, and other materials.

The principles apply to implementations in ion beam implantation systems, and to systems for large molecule deposition of boron and other species for atomic layer deposition or producing other types of layers or deposits, for instance by plasma immersion, including PLAD (plasma doping), PPLAD (pulsed plasma doping) and PI³ (plasma immersion ion implantation), Atomic Layer Deposition (ALD) or Chemical Vapor Deposition (CVD), for example.

B. Feed Materials for Cluster Ion Sources, in General

It is useful for efficiently implanting molecular ions which contain multiple atoms of an electrical dopant species such as the elements B, P, As, Sb, and In which lie in the periodic table on either side of the group IV elements of C, Si, Ge, and Sn, and also for efficiently implanting molecular ions which contain multiple atoms of elements such as C, Si, or Ge useful for modifying a semiconductor substrate to effectuate, for example, amorphization, dopant diffusion control, stress engineering, or defect gettering. Such molecular ions can be useful for fabricating integrated circuits with critical dimensions of 60 nm and less. Hereinafter, such ions will be collectively referred to as “cluster” ions.

The chemical composition of a singly charged cluster ion has the general form

M_(m)D_(n)R_(x)H_(y) ⁺  (1)

where M is an atom such as C, Si, or Ge useful for material modification of the substrate; D is a doping atom such as B, P, As, Sb, or In (from group III or IV of the Periodic Table) for implanting a charge carrier in to the substrate; R is a radical, ligand, or molecule; and H is a hydrogen atom. Generally, R or H are present simply as part of the complete chemical structure needed to produce or form a stable ion and are not specifically required for the implant process. In general H is not significantly detrimental to the implant process. The same should be true for R. For example it would be undesirable for R to contain a metallic atom such as Fe, or an atom such as Br. In the above equation m, n, x, and y are all integers greater than or equal to zero, with the sum of m and n greater than or equal to two, i.e, m+n≧2. Of particular interest in ion implantation are cluster ions with a high M and/or D atomic multiplicity, i.e those with m+n≧4, because of their improved efficiency for low energy, high dose implants.

Examples of cluster ions that can be used for material modification are those derived from adjoining benzene rings such as C₇H_(y) ⁺, C₁₄H_(y) ⁺, C₁₆H_(y) ⁺, and C₁₈H_(y) ⁺. Examples of cluster ions that can be used for doping are:

-   -   Borohydride ions: B₁₈H_(y) ⁺, B₁₀H_(y) ⁺.     -   Carborane ions: C₂B₁₀H_(y) ⁺ and C₄B₁₈H_(y) ⁺     -   Phosphorus hydride ions: P₇H_(y) ⁺, P₅(SiH₃)₅ ⁺, P₇(SiCH₃)₃ ⁺.     -   Arsenic hydride ions: As₅(SiH₃)₅ ⁺, As₇(SiCH₃)₃ ⁺.

One of ordinary skill in the art can appreciate the possibility of using cluster ions other than those listed in the examples above, including: ions containing Si and Ge for material modification, ions with different amounts and different isotopes of dopant atoms, and ions with different isomeric structures. Doubly charged cluster ions are also generally formed with a much smaller yield in which case they are not as useful for high dose, low energy implantation.

For example, the method of cluster implantation and cluster ion sources with respect to decaborane has been described by Horsky et al. in U.S. Pat. No. 6,452,338 and U.S. Pat. No. 6,686,595 hereby incorporated by reference. The use of B₁₈H_(x) ⁺ in making PMOS devices is disclosed in Horsky et al. in pending U.S. patent application Ser. No. 10/251,491, published as U.S. Patent Application No. U.S. 2004/0002202 A1, hereby incorporated by reference.

C. Large Carborane Molecules

The nature of these boron-containing materials and their ions is explained in the literature, see for instance Vasyukova, N. I. [A. N. Neseyanov Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1337-1340, June, 1985. Original article submitted Mar. 13, 1984. Plenum Publishing Corporation.]

The cluster molecule o-C₂B₁₀H₁₂ has been successfully vaporized and ionized, see FIG. 18. Good vapor flow is obtainable at about 42 C. C₄B₁₈H₂₂ is also a useful material.

D. Large Molecules of Carbon

In general, any hydrocarbon with a chemical formula of the form C_(n)H_(y), where n≧4 and y≧0 will increase the effective carbon dose rate into the silicon, and provide varying degrees of amorphization, in all cases being more beneficial than a monomer carbon implant. Flouranthane, C₁₆H₁₀, vaporizes at a temperature of 100 C, well suited to use in an electron impact ion source. Its vaporization temperature is similar to that of B₁₈H₂₂. A beam current of 0.5 mA enables the equivalent of 8 mA of carbon to be implanted on the wafer, at very low energy (about 1 keV per carbon atom). Ion beam currents of >1 mA are easily realized. Other carbon cluster materials are useful. For example, the following hydrocarbons may potentially be used:

-   -   2,6 diisopropylnaphthalene (C₁₆H₂₀)     -   N-octadene (C₁₆H₃₈)     -   P-Terphenyl (C₁₈H₁₄)     -   Bibenzyl (C₁₄H₁₄)     -   1-phenylnaphthalene (C₁₆H₁₂)

E. Large Molecules for N-Type Doping

As, P, and Sb are N-type dopants, i.e., “donors”.

For Sb, trimethystibines are good large molecule candidate feed materials, for instance Sb(CH₃)C₃.

For As and P, the ions are of the form AnHx⁺ or AnRHx⁺ where n and x are integers with n greater than 4 and x greater than or equal to 0, and A is either As or P, and R is a molecule not containing phosphorus or arsenic, which is not injurious to the implantation process.

Chemical Properties of Phosphorus-Bearing Compounds

The compounds phosphanes, organophosphanes and phosphides are seen to be potential sources for cluster phosphorus molecules and the subsequent ions for N-type doping. Examples include (1) phosphane, e.g., Heptaphosphane, P₇H₃, and Cyclopentaphosphane, P₅H₅, (2) Organophosphane, e.g., Tetra-tertbutylhexaphosphane, tBu₄P₆, Pentamethylheptaphosphane, Me₅P₇, (3) Phosphide, e.g., Polyphosphides: Ba₃P₁₄, Sr₃P₁₄ or Monophosphides: Li₃P₇, Na₃P₇, K₃P₇, Rb₃P₇, Cs₃P₇.

Cyclic phosphanes appear to be the most effective source of dopant clusters favorable to ionization and subsequent implantation with Heptaphosphane, P₂H₃, appearing to have the greatest potential of providing a simple cluster source for ion beam implantation.

Substitution of As for P in P_(n)H_(x) and P_(n)RH_(x) Compounds

Phosphorus-containing species and supporting synthesis techniques are theorized to allow direct substitution of the phosphorus atoms with arsenic to form similar arsenic species, due to similarity in the outer shell electron configuration and similar chemistry reactivity that same group elements exhibit. Molecular prediction software also indicates the similarity in substituting arsenic for phosphorus. The predicted molecular structure for As₇H₃ is nearly identical to P₇H₃ with differences being limited to the individual atomic radii of phosphorus and arsenic. Synthesis Pathways for P₇H₃ and As₇H₃ are analogous and interchangeable. In addition, since both Si and H are not injurious to devices formed on silicon wafers, the compounds As₇(SiH₃)₃ and As₅(SiH₃)₅ are very attractive, and are predicted to be stable compounds.

Furthermore, materials in the form of A_(n)RH_(x) may be formulated in a manner to allow selective removal of the phosphorus or arsenic containing portion independently of the remaining molecular structure, R. This characteristic may be employed to increase the level of safe transportation in that the complex feed material is less volatile, hence less susceptible to emissions than the pure component. The residual material may be left in the transport container and “recharged” in normal cycle operations. Furthermore, the R molecular portion may be removed prior to the targeted dopant containing species, discarded or recycled to provide an increased margin of safety during transportation. Synthesis pathways to develop numerous organometallic compounds are well documented and known within the art.

Other As and P-Bearing Compounds of Interest

In addition to the 6-membered ring in (P/As)₆, 5-membered rings have been obtained with R═Me, Et, Pr, Ph, CF₃, SiH₃, GeH₃ and 4-membered rings occur with R═CF₃, Ph.” (N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, Butterworth and Heinemann Ltd, 1984, pgs 637-697). Thus, carbonyl groups are directly interchangeable with silicon hydrides, as well known in the art. In addition, a silicon phosphide has also been identified: Si₁₂P₅. This material is seen to be extremely useful in ultra-shallow junction formation of Halos and S/D Extensions, and also for Poly Gate doping. The mass of Si₁₂P₅ is about 491 amu. Thus, extremely shallow implants can be per formed with this compound. In addition, since Si is routinely used for pre-amorphization prior to conducting the N-type drain extension implant, the Si₁₂P₅ implant would be self-amorphizing. It is likely there would not be deleterious end-of-range defects created by this implant, since the silicon would have about the same range as the P atoms, keeping damage very shallow. Such defects can be annealed out very effectively, since they tend to diffuse to the surface, when they annihilate.

A number of implementations of the inventive aspects have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other implementations are within the scope of the following claims. 

1. A flow interface device in the form of a thermally conductive valve block which defines at least one vapor passage, the passage associated with at least first and second vapor transfer interfaces, one interface comprising a vapor inlet located to receive vapor from a vaporizer of solid feed material and communicating with an inlet portion of the passage, and the other interface comprising a vapor outlet for delivery of vapor from an outlet portion of the passage to a vapor-receiving device, the valve block having at least one vapor valve and constructed to heat the passage and deliver vapor from the vaporizer to the vapor-receiving device.
 2. The flow interface device of claim 1 in which the vapor valve is a flow control valve for regulating the flow of vapor to an ion source.
 3. The flow interface device of claim 1 in which a vapor valve is a valve system that enables vapor flow to an ion source of vapor entering through the vapor inlet and another flow to the ion source.
 4. The flow interface device of claim 3 in which another flow enabled is flow of vapor from another vapor inlet defined by the valve block.
 5. The flow interface device of claim 3 in which another flow enabled is flow to the ion source is flow of a reactive cleaning gas.
 6. The flow interface device of claim 3 including at least two valve systems in the valve block, a first valve system enabling vapor flow to the ion source of vapor entering through said vapor inlet, and enabling flow to the ion source of vapor from another vapor inlet defined by the valve block, and a second selector valve system enabling flow of vapor from a vapor inlet defined by the valve block, or, alternatively, closing all vapor flow and permitting flow to the ion source of a reactive cleaning gas.
 7. The flow interface device of claim 1 in which at least two vapor inlets defined by the valve block are located to receive vapor from respective vaporizers, the two vapor inlets associated with respective inlet passage portions, flows through the inlet passage portions being enabled by the first valve system, the inlet passage portions merging following the first valve system into a common passage portion, and the second valve system is arranged to selectively enable flow through the common passage portion to the vapor-receiving device, or, alternatively, flow of the reactive cleaning gas to the vapor-receiving device.
 8. The flow interface device of claim 7 in which a further valve comprising a flow control valve is associated with the common passage portion for regulating flow of vapor to the vapor-receiving device.
 9. The flow interface device of claim 3 in which the valve system comprises a spool valve acting as a selector to permit only one of said flows at a time.
 10. The flow interface device of claim 1 in which the valve block is associated with a heater controlled to maintain the temperature of the valve block higher than that of a vaporizer from which it receives vapor.
 11. The flow interface device of claim 1 in which the valve block defines a mounting region constructed to receive and support a vaporizer.
 12. The flow interface device of claim 11 including thermal insulation insulating the valve block from the vaporizer to define respective separate thermal control regions to enable maintenance of valve block temperature higher than that of the vaporizer.
 13. The flow interface device of claim 11 having a connector constructed, with mounting motion of a vaporizer with respect to the valve block, to mate with a matching connector of the vaporizer, for connecting the vaporizer electrically to a heating control system.
 14. The flow interface device of claim 11 in which the valve block defines a receptacle having support surfaces for receiving a support projection of a vaporizer to thereby support the vaporizer during vaporizer heating and vapor transfer.
 15. The flow interface device of claim 14 in which the support projection is a lateral projection defining a lateral vapor flow passage, the projection having a peripheral side surface and an end surface, and peripheral and end thermal insulation portions are provided to enable thermal isolation of the valve block from the projection of the vaporizer.
 16. The flow interface device of claim 14 in which the receptacle of the valve block is constructed to receive the support projection of the vaporizer by linear sliding motion of the projection, the flow interface device mounting an electrical connector that is constructed, with mounting motion of a vaporizer relative to the valve block, to slideably mate with a matching electrical connector of the vaporizer for connecting the vaporizer electrically to a control and heating system.
 17. The flow interface device of claim 16 in which the electrical connector includes a pneumatic connector for supplying controllable compressed air to the vaporizer for selectively actuating a valve of the vaporizer.
 18. The flow interface device of claim 1 in which the vapor valve is a flow control valve, the interface device being associated with a power supply and heating system for receiving sensed temperature signal from a vaporizer and for applying electric heating current to the vaporizer to cause the vaporizer to heat sufficiently to produce vapor of the solid feed material of pressure greater than that required by the vapor-receiving device, and in the range that enables the flow control valve to regulate vapor flow to the ion source.
 19. The flow interface device of claim 1 combined with a vaporizer, the vaporizer containing solid feed material capable of producing ionizable vapor.
 20. The flow interface device of claim 1 combined with a vapor-receiving device in the form of an ion source constructed to produce ions for use in semiconductor manufacture.
 21. The flow interface device of claim 1 in combination with an ion beam implanter in which the vapor-receiving device comprises a high voltage ion source capable of ionizing vapor to produce a beam of ions for ion implantation.
 22. The flow interface device of claim 19 in which the solid feed material comprises a cluster compound capable of producing vapor for the production of cluster ions.
 23. The flow interface device of claim 22 in which the cluster compound comprises a cluster boron compound.
 24. The flow interface device of claim 23 in which the compound comprises a borane or a carborane.
 25. The flow interface device of claim 24 in which the compound comprises B₁₀H₁₄, B₁₈H₂₂, C₂B₁₀H₁₂ or C₄B₁₈H₂₂.
 26. The flow interface device of claim 22 in which the cluster compound comprises a cluster carbon compound.
 27. The flow interface device of claim 26 in which the cluster compound comprises C₁₄H₁₄, C₁₆H₁₀, C₁₆H₁₂, C₁₆H₂₀, C₁₈H₁₄; or C₁₈H₃₈.
 28. The flow interface device of claim 22 in which the cluster compound comprises a compound for N-Type doping.
 29. The flow interface device of claim 28 in which the compound comprises an arsenic, phosphorus or antimony cluster compound.
 30. The flow interface device of claim 29 in which the compound comprises an arsenic or phosphorus compound capable of forming ions of the form A_(n)H_(x) ⁺ or A_(n)RH_(x) ⁺, where n and x are integers with n greater than 4 and x greater than or equal to 0, and A is either As or P and R is a molecule not containing phosphorus or arsenic and which is not injurious to the implantation process.
 31. The flow interface device of claim 29 in which the compound comprises a phosphorus compound selected from the group consisting of phosphanes, organophosphanes and phosphides.
 32. The flow interface device of claim 29 in which the compound is P₇H₇.
 33. The flow interface device of claim 29 in which the compound comprises an antimony compound that comprises a trimethylstibine.
 34. The flow interface device of claim 33 in which the compound comprises S_(b)(CH₃)C₃.
 35. The flow interface device and vaporizer of claim 22 in combination with an ion beam implanter in which the vapor-receiving device comprises a high voltage ion source capable of ionizing vapor produced from the solid feed material for ion implantation.
 36. The combination of the flow interface device of claim 1 with a vapor-receiving-device in the form of a high voltage ion source and the flow-interface device is mounted for support upon an electrical insulator.
 37. The combination of claim 36 in which the insulator is an insulator bushing that also supports the ion source to which the vapors are delivered.
 38. The flow interface device of claim 36 in combination with an ion beam implanter in which the vapor-receiving device comprises a high voltage ion source capable of ionizing the vapor to produce a beam of ions for ion implantation.
 39. The flow interface device of claim 1 including a gas purge system for removing vapor from the vapor inlet passage of the valve block prior to disconnecting the vaporizer from the valve block.
 40. The flow interface device of claim 1 in which the valve block defines a delivery passage for a process gas.
 41. The flow interface device of claim 40 constructed so that the process gas is selectively directed through a passage through which reactive cleaning gas is at other times directed.
 42. The flow interface device of claim 1 in which the valve block includes a delivery extension defining at least two flow paths to the vapor-receiving device, at least one of which is constructed to convey vapor from solid feed material and another is constructed to deliver a process gas or a reactive cleaning gas.
 43. The flow interface device of claim 2 in which the flow control valve is a throttle-fly type valve.
 44. The flow interface device of claim 4 in which the valve system permits only one of the vapor flows at a time.
 45. The flow interface device of claim 44 in which the valve system comprises a spool valve.
 46. The flow interface device of claim 420, for use with vaporizers containing the same feed material, comprising a valve system that permits flow from at least two vaporizers simultaneously.
 47. The flow interface of claim 46 in which the valve system is constructed for a second mode of action in which the valve system permits only one of the vapor flows at a time.
 48. A flow interface device for an ion source constructed for use as the ion source for an ion beam implanter, the interface device being in the form of a thermally conductive valve block which defines at least one vapor passage, the passage associated with at least first and second vapor transfer interfaces, one interface comprising a vapor inlet located to receive vapor from a vaporizer and communicating with an inlet portion of the passage, and the other interface comprising a vapor outlet for delivery of vapor from an outlet portion of the passage to the ion source, the valve block constructed to heat the passage and deliver vapor from the vaporizer to the ion source, a flow control valve associated with the passage for regulating the flow of vapor to the ion source, and a valve system that enables vapor flow to the ion source of vapor entering through the inlet and another enables flow to the ion source.
 49. The flow interface device of claim 48 associated with a power supply and control system for causing the vaporizer to heat sufficiently to produce vapor of the solid feed material of pressure greater than that required by the ion source, and in the range controllable by the flow control valve.
 50. The flow interface device of claim 48 in which the flow control valve is a butter-fly type valve.
 51. The flow interface device of claim 48 in which another flow enabled is flow of vapor from another vapor inlet defined by the valve block.
 52. The flow interface device of claim 48 in which another flow enabled is flow to the ion source of a reactive cleaning gas.
 53. The flow interface device of claim 48 including at least two valve systems in the valve block that enable flow, a first valve system enabling vapor flow to the ion source of vapor entering through the vapor inlet, and enabling another flow to the ion source of vapor from another vapor inlet defined by the valve block, and a selector valve system enabling flow of vapor from a vapor inlet defined by the valve block, or. alternatively, closing all vapor flow and enabling flow to the ion source of a reactive cleaning gas.
 54. The flow interface device of claim 53 in which vapor inlet passages associated with at least two vapor inlets located to receive vapor from respective vaporizers are controlled by the first valve system following which the inlet passage portions merge into a common passage, and the second valve system selectively controls flow through the common passage portion to the ion source, or alternatively flow of the reactive cleaning gas to the ion source, the flow control valve being associated with the common passage for regulating flow of vapor to the ion source.
 55. The flow interface device of claim 54 in which a valve comprises a spool valve.
 56. The flow interface device of claim 48 in which the valve block is associated with a heater controlled to maintain the temperature of the valve block higher than that of a vaporizer from which it receives vapor.
 57. A method of producing vapor employing the device or combination of claim
 1. 58. The method as recited in claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising a cluster molecule.
 59. The method of claim 58 employing an ion source capable of ionizing vapor produced from the solid material.
 60. The method of claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising C₁₄H₁₄, C₁₆H₁₀, C₁₆H₁₂, C₁₆H_(2O), C₁₈H₁₄ or C₁₈H₃₈.
 61. The method of claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising compound for N-Type doping.
 62. The method of claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising an arsenic, phosphorus or antimony cluster compound.
 63. The method of claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising an arsenic or phosphorus compound capable of forming ions of the form A_(n)H_(x) ⁺ or A_(x)RH_(x) ⁺, where n and x are integers with n greater than 4 and x greater than or equal to 0, and A is either As or P and R is a molecule not containing phosphorus or arsenic and which is not injurious to an ion implantation process.
 64. The method of claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising a phosphorus compound selected from the group consisting of phosphanes, organophosphanes and phosphides.
 65. The method of claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising P₇H₇.
 66. The method of claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising an antimony compound that comprises a trimethylstibine.
 67. The method of claim 57 further including the step of employing flow interface devices in generation, delivery and utilization of vapor from solid material comprising
 68. The method of treating a semiconductor device or semiconductor material comprising using the flow interface device or vapor delivery system of claim 1 to produce cluster ions, and using the ions in the treatment.
 69. The method of claim 68 in which the method of treating comprises ion implantation.
 70. The method of claim 69 in which the method of treating comprises ion beam implantation.
 71. A system for producing vapor along a flow path from a group of vaporizers at mounting stations of a vapor delivery system comprising subgroups of vaporizers, one of the subgroups containing at least two vaporizers containing the same solid feed material and another group containing at least one vaporizer containing a different solid feed material, at least one vaporizer of the group containing material comprising a cluster molecule, the system including a control system enabling the subgroup of vaporizers containing the same solid feed material to simultaneously provide vapor along the path and preventing simultaneous flow through the path of vapor from the other subgroup.
 72. The system of claim 71 in which the system is an electro-mechanical control system.
 73. The system of claim 71 including a vapor flow control that includes two variable conductance flow devices in series along the flow path, the down-stream device comprising a throttle valve and the up-stream device enabling adjustment of pressure of the vapor reaching the throttle valve.
 74. A system for producing vapor along a flow path from a group of vaporizers at mounting stations of a vapor delivery system comprising at least two vaporizers containing the same solid feed material of a cluster molecule wherein a control system is constructed to enable the two vaporizers to operate simultaneously.
 75. The system of claim 74 including a vapor flow control that includes two variable conductance flow devices in series along the flow path, the down-stream device comprising a throttle valve and the up-stream control enabling adjustment of pressure of the vapor reaching the throttle valve.
 76. The method of producing ions for implantation comprising ionizing vapor received from claim
 71. 77. The method of claim 76 in which ions produced are formed into a beam for ion implantation.
 78. A system for producing vapor along a flow path from a vaporizer containing material comprising a cluster molecule comprising a vapor flow control that includes two variable conductance flow devices in series along the flow path, the downstream device comprising a throttle valve and the up-stream control enabling adjustment of pressure of the vapor reaching the throttle valve. 